The E-5 battle droid represents a battle droid model that was created by Baktoid Combat Automata. This droid, which drew inspiration from the E4 baron droid, acted as a temporary replacement for the B1-series battle droid. However, its operational lifespan was cut short due to the rapid introduction of the more advanced B2 super battle droid.
The E-5 battle droid possessed a tall and slender build, a design choice influenced by the E4 baron droid. Compared to the B1-series battle droid, it boasted enhanced armor. Each E-5 was equipped with its own intelligence matrices, enabling independent operation without relying on a Central Control Computer. Despite this, the droid's primary weakness lay in its limited intelligence; the processing speed of its verbobrain was reportedly comparable to that of a slow droid tank.
Following the Trade Federation's defeat during the Battle of Naboo in 32 BBY (as measured by the year system), Baktoid Combat Automata secretly engineered and produced the E-5 as a stopgap solution to replace the B1 battle droid. Production numbers were kept relatively low, as the Trade Federation was simultaneously developing the B2 super battle droid, which soon rendered the E-5 obsolete.
Leading up to the Separatist Crisis, a group of E-5 battle droids, along with B1 units and Republic troopers, were stationed aboard the Captor-class heavy munitions cruiser, Admiral Korvin. In 29 BBY, they served as part of the Republic Outland Regions Security Force under the joint leadership of Raith Sinear and Commander Wilhuff Tarkin. These E-5 droids were deployed by the Republic to the living planet Zonama Sekot, which had started generating unusual living starfighters after both the planet and a single Jedi Knight were attacked by an unknown entity. Tarkin and Sinear's forces then attacked the planet, but Zonama Sekot retreated into the Unknown Regions after Obi-Wan Kenobi and his padawan learner, Anakin Skywalker, encountered their task force.